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I got asked about #RADE work. It is impressive, but it's solving an HF specific problem. The Watterson channel model, the -2 dB SNR operation, and analog style degradation is tuned for a propagation environment where we see ionospheric multipath with fade periods measured in hundreds of milliseconds. It's a narrow (and important) niche, but it doesn't generalize upward in frequency where the channel is very different and higher bandwidth signals are legal.
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Anyone with experience on #non-coherent #digital #communications #demodulation - we're looking at how to better integrate phase ambiguity resolution with respect to #MSK. In other words, avoid having to have a #differential encoder/decoder by using the two pre-existing #Costas loops out of phase with each other, to provide the same functionality. If this is "old news" please let us know?
Thank you @OpenResearchIns for the opportunity and support.
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Do you know about #LTE transmitters and can help with some questions? I have what I hope is a simple question about space frequency block coding #SFBC implementation.
SFBC is a special case of space time block coding (#STBC) in #mimo, where we get a stream of transmitter samples that are supposed to go out the door and on the air, and we use some tricks to get better reliability in #multipath environments.
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Our scheduled #RATPAC presenter last night had to cancel, so I stepped in and talked about the #FCC #symbol rate rules change. Recording should be up soon.
That's right, the #baud rate limit is going away. HF bands get a 2.8 kHz bandwidth limit for data modes. That is in the report and order.
A request for comments about 2200 m, 630 m, VHF, and UHF #bandwidth limits is the second part of this rules change document.
Read it here: https://docs.fcc.gov/public/attachments/DOC-397992A1.pdf
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Excellent retrocomputing video here:
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Today in the lab? We're on to #polyphase filter banks in #fpga implementations, all #opensource work.
Thanks to everyone that helps make stuff like this happen, or supports those of us that spend the time to develop it, whether it's at @OpenResearchIns or someplace else!
You are the heroes we don't deserve, yet rely upon to fully enjoy advanced #digital #communications and #sdrs. :D
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I've been on #17m #ft8 building up contacts for whatever awards and cards I get. It's been *super* fun for several reasons.
1) I know why ft8 works so well. I know a lot about #LDPC codes and #digital comms. It's a joy to use this mode. It's literally the best FEC outside of #Polar codes. We rock!
2) It seems to tick off the local very old white male DX club to no end that "lazy people are getting dxcc for nothing!" rawr grumble fulminate etc
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Progress on a #polynomial signals representation project:
This is a new/old idea that makes specific promises, has some research, but doesn't have a lot of practical radio development or useful applications (yet).
Well, that's what we're here for!
There's repository started over at @OpenResearchIns
at https://github.com/OpenResearchInstitute/Polynomial_Signals_RepresentationTrying to put together a coherent tutorial so that ordinary radio enthusiasts can get some traction.
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Trying to get the #mathworks #buildroot SD card image built. This is for a #zynq #zc706, using the build.py straight out of the repo on supported hardware for supported versions of MATLAB, HDL Coder, and Vivado.
Lots of errors. Could use some opinions and advice.
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I've been a member of San Bernardino Microwave Society #SBMS for many years.
I just wrapped up a couple of years serving as Recording Secretay. I took minutes. I included a summary of all member roundtable reports. I helped with multiple #ARRL #club #grant applications and was involved with the #ARDC Cactus Network grant applications.
I have some opinions, shared by the rest of the board, about how a sudden influx of money has affected one of the best technical #hamradio clubs in the USA.
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Yesterday we got the #VHDL #testbench for part of our #opensource #DVB-S2 #fpga amateur #satellite encoder working (and it PASSED!) on the command line, using GHDL. This is great! 🌈
The parallel effort in Xilinx Vivado didn't work, because vunit (a necessary component of the testbench) doesn't support xsim in Vivado.
This word salad boils down to "open source helps advanced digital communications in amateur radio"
The support for vunit working in Vivado has been a filed issue since 2017.
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Yesterday we got the #VHDL #testbench for part of our #opensource #DVB-S2 #fpga amateur #satellite encoder working (and it PASSED!) on the command line, using GHDL. This is great! 🌈
The parallel effort in Xilinx Vivado didn't work, because vunit (a necessary component of the testbench) doesn't support xsim in Vivado.
This word salad boils down to "open source helps advanced digital communications in amateur radio"
The support for vunit working in Vivado has been a filed issue since 2017.